Jessica Alba's The Honest Company, built on a reputation of using natural ingredients in its household products, is denying an explosive new report that its laundry detergent contains an undisclosed harsh irritant.

Two independent lab tests commissioned by the The Wall Street Journal found that the company's liquid laundry detergent contains sodium lauryl sulfate (SLS) — a chemical that breaks down surface tension between molecules, but can irritate skin.

Jessica Alba’s The Honest Company may have included an ingredient in its liquid laundry detergent that the company has long claimed not to use.

(Getty Images for Honest.com)

SLS is found in a number of other mainstream brands' shampoos, toothpastes and detergents, but The Honest Company has made a big point of advertising its products as free of the chemical.

"Our findings support that there is a significant amount of sodium lauryl sulfate (in the detergent)," a chemist at Impact Analytical, one of the two labs, told the Journal.

The Honest Company, however, vehemently denies the labs' findings and accused the newspaper of using “junk science.”

Alba and The Honest Company celebrate the launch of the Springtime in Paris Diaper Collection on Wednesday in New York City.

(Dimitrios Kambouris/Getty Images for The Honest Comp)

“Despite providing The Wall Street Journal with substantial evidence to the contrary, they falsely claimed our laundry detergent contains Sodium Lauryl Sulfate,” a rep for the company said in a statement to the Daily News.

The company says it uses sodium coco sulfate, a less-irritating alternative ingredient instead.

“The Wall Street Journal has been reckless in the preparation of this article, refused multiple requests to share data on which they apparently relied and has substituted junk science for credible journalism,” the rep said.

A spokesman for the Journal says the oultlet stands by its reporting and the experts it consulted, and that The Honest Company had "numerous opportunities to respond to our findings."

The newspaper's report comes just one month after a couple filed a lawsuit in U.S. District Court in Manhattan alleging that Honest fradulently labels products as natural or chemical free. A similar $5 million class-action lawsuit was filed in September by a San Francisco man.

Alba, 34, co-founded Honest four years ago, and has watched as the company has grown into a $1 billion empire based on a reputation of producing safer and more natural household products than other alternatives at the super market.